I have 2 short blocks I am working on for swapping in place of the 534 SD engine .I have a low mileage 460 RV motor with new rods and pistons ,hope to reach 9-1 compression .have a .040 over bore 429 truck engine with steel crank that is ground 20/20 .both engines will get new bearings and rings ,and a hone job.what ever engine I install will get a comp ex256h hydraulic cam with matching spring .the heads are the Procomp Ebay heads ,that will receive a valve job and new springs and adjustable rocker arms ,what do you guys think and say ?

 

A larger engine will have more torque and horsepower with all the same parts otherwise. The 429 Lima is a truck engine that's designed to handle a higher duty cycle than the 460. Piston designs are different and getting 9:1 compression with that cylinder head will probably be impossible without angle milling the heads.

 

the 429 engine is .040 over bore ,and is flat top and has 2 small valve reliefs ,and it appears to be 0 decked .I weighed a 429 rod/piston with bearings and rings ,and it weighed 100 grams more then the stock 460 rod/piston combo ,but I did not include the rings and bearings with it .the normal stamp numbers on the rods don't match ,a number 2 rod with a number 3 rod cap .I see some numbers stamped on the bottom weight pad ,but not all rods are stamped there .I screwed up not numbering the rods when I removed them .I will have the whole rotating rebalanced .I am trying to polish the crank with 3000grit and PB blaster ,it worked ok on the 460 truck crank .I bought new 5140 rods from Competition products ,already sized for install for $250 ,but the weights range from 898-907 grams ,so I want them matching .the new pistons are heavier the stock pistons ,970 grams with a 7cc dish .I will get the 460 rotating balanced also .I have 1 more 429 truck motor to retrieve from up north ,I want it for the truck flywheel ,the bigger oil pan and the cast iron timing cover and front motor mount .I hope to run a thin MLS head gasket to keep the compression ratios around 9-1

 

Have you checked the size of the combustion chambers on your heads yet? I think that they are around 97cc or so on the Pro Comps. That's going to put you down around 8:1 or so on a 429. Check it out.

Also, if you're set on running a cam from Comp a 252H would be a better choice for the application.

 

I already have the whole ex256h cam kit ,$490 total from Ebay ,cam,lifters,springs,retainers and locks ,and timing chain set .the 429 is 4.400 bore ,the block was decked,I did not check for how far the pistons are down in the bore .the pistons are not dished ,but have very small valve reliefs.I used a compression calculator at another site ,and it showed me at 9.36 compression .I have some plexiglass and might make chamber plate for cc ing the chamber .the heads need the valve bowls cleaned up and they need a good valve job ,so I might gain volume there .I might get the heads milled if I need to .the pistons I got for the 460 raised the compression from 8.09 to 9.06 compression,the stock pistons had a .230 deep dish ,been toad this was a 23 CC dish .the new pistons have only a .070 dish ,for a 7cc dish .alot depends on the bore and thickness of the head gaskets .I think I need a .040 or thicker MLS head gasket for the aluminum heads .thanks for all you input

 

dropped the heads off with a old school engine builder who knows how to build pump gas engines .I will drop the rotating assembly off at the engine machine shop for balancing .